AZT not equivalent to HAART to prevent mother-to-child transmission in a Botswana programme

Polly Clayden HIV i-Base

A study, first presented at CROI 2011, compared mother to child transmission rates for women receiving AZT (with or without single dose NVP) or HAART in pregnancy in the Botswana national programme. [1] We reported these data in the May issue of HTB. [2]

This prospective observational study conducted between February 2009 and April 2010, showed of 428 infants born to either 258 mothers receiving HAART or 170 mothers receiving AZT, those in the AZT group were significantly more likely to be HIV infected than those whose mothers received AZT, relative risk 13.9 (95% CI 1.8-108), p=0.001. There were nine transmissions in the AZT group and one in the HAART group.

Notably the women eligible for HAART had CD4 counts <250 cells/mm3 and those receiving AZT >250 cells/mm3.

Scott Dryden-Peterson and colleagues reported complete results in an online article published ahead of print in JAIDS. [3]

The overall findings are unchanged from those presented previously but the article includes some more details and discussion. The authors write: “Our findings do not support the equivalence of zidovudine and HAART for the prevention of MTCT.” In the study over half (5/9) infections in the AZT group occurred in women with CD4 counts <350 cells/mm3.

The authors observed difficulties with the delivery of single dose NVP in this cohort (women receiving <4 weeks of AZT were eligible) with only 5 (22.7%) women receiving this. Preterm delivery rather than delayed initiation was the main reason in this cohort for short duration of antenatal antiretrovirals, with nearly one-third of infants born preterm or of low birth weight.

They add that the findings from this study indicate that a strategy to provide HAART for all HIV-positive pregnant women, as is being piloted in Botswana, could almost eliminate infant HIV infection.


Although better transmission results for women not indicated for treatment have been demonstrated in trials, programmers have often remarked that having a two-tiered approach to PMTCT is too complicated to implement.


  1. Dryden-Peterson S et al. Effectiveness of Maternal HAART vs ZDV to Prevent MTCT in a Programmatic Setting: Botswana. 18th CROI. Boston. February 2011. Poster abstract 740.
  2. Clayden P. HAART more effective than AZT monotherapy in the Botswana PMTCT programme. HTB May 2011.
  3. Dryden-Peterson S et al. Highly active antiretroviral therapy versus zidovudine for prevention of mother to child transmission in a programmic setting, Botswana. JAIDS. Publish ahead of print DOI: 10.1097/QAI.0b013e31822d4063.

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